Rotary impact tool



P. WQMARTIN ETAL ROTARY IMPACT TOOL Jan. 8, 1963 2 Shets-Sheet 1 Filed Dec. 2, 1960 Jan. 8, 1963 P. w. MARTIN ETAL 3,072,232

ROTARY IMPACT TOOL Filed Dec. 2, 1960 2 Sheets-Sheet 2 INVENT P1704 M. M1927 RWBEET E". 844%? By 21% /7A United States Patent 3,072,232 ROTARY IMPACT TOOL Paul W. Martin and Robert E. Baker, Spur-infield, Ohio, assignors to The Airetool Manufacturing Company, Springfield, Ohio, a corporation of Ohio Filed Dec. 2, 1960 Ser. No. 73,436 3 Claims. (Cl. 19230.5)

This invention relates to pneumatic tools and is particularly concerned with a rotary pneumatic tool of the impact type such as are employed for running down and tightening nuts and machine screws, and the like.

The present invention has for a primary objective the provision of a rotary impact tool of the nature referred to, which has an improved efiiciency of operation over what has been had heretofore with rotary impact tools.

A still further object of the present invention is the provision of a rotary impact tool which will be conserving of compressed air and which will utilize a minimum of compressed air, particularly during the run-down period.

A still further object of this invention is the provision of a rotary impact tool which can readily be adjusted to control the ultimate torque developed thereby.

Still another object of this invention is the provision of a rotary impact tool which has identical operating characteristics in both directions of rotation and which can readily be reversed.

Still another object of this invention is the provision of a rotary impact tool which is extremely strong and substantially free from breakage but which can be manufactured economically.

These and other objects will become apparent from the following detailed description and accompanying drawings wherein:

FIGURE 1 is a perspective view of a rotary impact tool according to the present invention;

FIGURE 2 is a side view of the tool drawn at enlarged scale and partly in section;

FIGURE 3 is an exploded perspective view showing the principal operating parts of the impact developing portion of the tool;

FIGURE 4 is a view showing details in connection with the construction of a cam element forming a part of the impact developing mechanism;

FIGURE 5 is a view showing details in connection with the construction of a spindle forming the portion of the impact developing mechanism that receives the impacts and delivers them to a tool;

FIGURE 6 is a sectional View indicated by line 6-6 on FIGURE 2 showing the engagement of an actuator that is driven by the pneumatic motor and which actuator delivers torque into the impact developing portion of the mechanism;

FIGURE 7 is a sectional view indicated by line 7-7 on FIGURE 2. showing the relationship of the engagement cam member of the device relative to the spindle when the actuator and the developing cam are in their FIGURE 6 position;

FIGURES 8 and 9 are views corresponding to FIG- URES 6 and 7, respectively, but show the engagement cam member following the delivering of an impact to the spindle and just as it disengages from the spindle;

FIGURES 10 and 11 are sectional views corresponding to FIGURES 6 and 7, respectively, but showing the engagement cam member and spindle after the engageice ment cam has been released from the spindle and has rotated about degrees beyond its point of disengage ment with the spindle;

FIGURES l2 and 13 are views corresponding to FIG- URES 6 and 7, respectively, but showing the engagement cam member rotated about degrees illustrating the manner in which the engagement cam is cammed back into position to engage the spindle upon further relative rotation of the engagement cam and spindle; and

FIGURES 14 and 15 are views corresponding to FIG- URES 6 and 7, respectively, but showing the engagement cam member rotated nearly 360 degrees: from its FIG- URE 6 position and approaching the position where it will again deliver an impact to the spindle.

Referring to the drawings somewhat more in detail the rotary impact tool according to the present invention is generally shown in FIGURE 1, wherein it will be seen to comprise a motor case portion It having a pistol grip handle 12. There is attached to the motor case portion 10 a hammer case portion 14 from which projects the end of a spindle 16, with the said end being adapted for detachably receiving tools, such as sockets, and the like, with the tools being retained on the spindle as by the spring pressed ball detent 18. Other tool retaining means such as a pin could, of course, be employed.

Motor case portion 16) has mounted therein a rotary pneumatic motor, the details of which form no part of the present invention and are, therefore, not illustrated. The pistol grip handle 12, however, includes a valve 20 which is adjustable for controlling the rate of delivery of air to the air motor, thereby to control the ultimate torque developed on a tool carried on the end of spindle 16.

A reversing valve 22 is also included in the motor case portion and can be shifted to obtain clockwise or counterclockwise rotation of the spindle. A trigger 24 is provided by means of which the supply of air to the air motor can readily be controlled by the operator of the tool.

FIGURES 2 through 7 will disclose more in detail the construction of the impact developing portion of the tool, which is the particular portion of the device with which this application is concerned.

As will be seen in FIGURE 2 the hammer case 14 has therein a hammer member 26 which fits relatively loosely within the hammer case so as to be easly rotatable therein. By relatively loosely is meant clearances on the order of about nd of an inch on the radius. This hammer member is also journaled on spindle 16 as by bushings 28, 3! located in holes at the opposite ends of the hammer member. These bushings may be hardened steel, for example. Bushing 28 bears directly on spindle 16, whereas bushing 30 bears on the shank 32 of an actuator member which, in turn, receives a reduced diameter part 34 on the end of spindle 16 opposite the tool receiving end thereof.

The hammer member 26 has a hole 36 extending laterally therethrough which is rectangular in cross-section, as will be best seen in FIGURES 3, 6 and 7. Loosely mounted in this rectangular hole 36 is an engagement cam member 38. Engagement cam member 38, as will be seen in FIGURE 6, is dimensionally smaller laterally than the inside for the hammer case. The hammer case, for example, in the tool illustrated, has an inside diameter of 2% inches, whereas the dimension laterally of the engagement cam between its curved sides is 2 inches.

The engagement cam is thus free to travel laterelly of the hammer case and within hole 36 in the hammer member 26 a distance of A of an inch.

The hammer member 26 also has positioned thereinan actuator member 40 which has the shank portiotn, previously referred to, that extends into bushing 3% inside the air motor end of the hammer member. Actuator if has a bore 42 that receives the reduced diameter portion 34 of the spindle at one end, and this bore is splined at the other end for receiving the splined end of the output shaft 44 of the air motor in the air motor case.

At this point it will be appreciated that rotation of the air motor in either direction will cause rotation of actuator member 40 on the longitudinal axis of the impact tool and which axis coincides with the axis of the spindle 16. Actuator member 4-0 comprises a pair of oppositely directed wing portions 46 which have their one side forming a wide angle V-shaped recess, within which recess there projects an extension 48 of the engagement cam member 38.

Projection 48 is provided with surfaces which con verge towards the central axis of the engagement can member and are adapted for engagement by the surfaces 52 of the portions 46 of the actuator member which also converge toward the axis of the actuator member.

As will be seen in FIGURE 6, the aforementioned surfaces of the extension 48 of the engagement carn, one of said surfaces being indicated at 50 in FIGURE 4, are radial surfaces inclined at an angle of 45 degres from a center line between the two surfaces. FIGURE 6 will also show that the corresponding surfaces 52 of the actuator member 40 are inclined at angles of about 46% degrees from the same center line.

This arrangement provides for sufficient clearance between the surfaces 50 and their corresponding surfaces 52 to permit the lateral movement of the engagement cam member laterally in hole 36 in the hammer member 26, above referred to, when there is relative rotation between the actuator member and the engagement cam member, as will be explained hereinafter.

The engagement cam member, as will be seen in FIG- URE 4, has a central bore therethrough which is formed with two inwardly projecting impact ledges 54. Each impact ledge has a surface parallel with a transverse center line 56 of the engagement cam member and spaced from the center line a distance of X, which will vary with the size of the the tool, which in the present case, for a tool useful for running down screws and nuts up to about /2 inch, amounts to A of an inch.

Each impact ledge has a trailing side opposite the impact surface 54 indicated at 58 and which is inclined at an angle of about 60 degrees to center line 56. Surface 58 forms a camming surface to move the engagement cam member laterally in hole 63 in the hammer member 26, as will be described hereinafter.

The portion of the spindle 16 which is located inside the bore through the engagement cam and which receives impacts from the impact ledges of the engagement cam is indicated in FIGURE 5.

In FIGURE it will be seen the spindle 16 comprises an anvil part 60 which has surfaces 62 on the opposite sides thereof that converge'generally toward the center of the spindle but which are set inwardly from true radii a distance also equal to X, and in the present case amouting to of an inch. These surfaces include an angle of about 165 degrees therebetween, as is indicated in FIGURE 5. The surfaces 62 receive impacts from the impact ledge 54 of the engagement cam and the anvil portion 66 of the spindle also cooperates with the cam surfaces 58 of the said impact ledges to return the engagement cam member to effective position prior to each impact.

For explaining the manner in which repetitive imparts are delivered to the spindle, reference may be had to FIG- URES 6 through 15, which show the conditions of operation of the tool according to this invention in one direction of rotation.

In FIGURE 6 the actuator 40 is in engagement with the cam engagement member, which at this time is shifted leftwardly in hole 36 in the hammer member 26. As will be seen in FIGURE 7, with the engagement cam shifted leftwardly in the hammer member, the impact ledge at the right side of the engagement cam is in engagement with the adjacent surface of the anvil portion of the spindle. The parts of the tool are now in the position they will occupy for a free run-down of a nut or screw in a clockwise direction of rotation. The cam engagement member will be held in the position illustrated as it rotates by a combination of friction and centrifugal force acting thereon. It is to be noted, however, that the actuator is delivering a force against the engagement cam in the direction of the arrow 7!} in FIGURE 6, and which force is absorbed against the fiat side of hole 36 in the hammer member. The force is at an angle to the flat surfaces of the hammer member and thus comprises a component normal to the surfaces and a component directed through the hole, and which component urges the engagement cam member in a direction to disengage its active driving ledge from the anvil portion of the spindle.

So long as the spindle encounters no substantial resistance the engagement cam member will not be disengaged therefrom; however, upon the spindle encountering a predetermined resistance, the engagement cam member is shifted rightwardly and the condition which contains at the instant of disengagement of the driving ledge of the cam engagement member from the anvil portion of the spindle, as illustrated in FIGURES 8 and 9.

With the engagement cam member released from the spindle the engagement cam member and the actuator and the hammer member are free to rotate relative to the spindle. The parts are shown in this condition of free rotation in FIGURE 10, which shows the engagement cam member and hammer member rotated about degrees from the FIGURES 8 and 9 positions.

Continued rotation of the engagement cam member and hammer member will bring the cam portion of the cam surface 58 of the active impact ledge of the cam engagement member into engagement with the edge of the anvil opposite the active side thereof and the engagement cam member will be cammed thereby back into its original position.

The camming of the engagement cam member back to its original position is illustrated in FIGURES l2 and 13, which show the parts in a position where the engagement cam member and hammer member have rotated nearly degrees from their FIGURES 6 and 7 positions. The engagement cam member is now in position to deliver another impact to the anvil of the spindle, as will be apparent from the positions of the parts in FIGURES 14 and 15, which show the active ledge of the engagement cam member again approaching the active impact receiving ledge of the anvil portion of the spindle. It is understood that, as before, the engagement cam member will remain in its active position after being cammed into that position on account of the centrifugal force acting thereon. It will also be evident that on account of the symmetrical arrangement of the spindle and the engagement cam member, hammer and actuator, exactly the same conditions of operation will obtain in both directions of rotation.

The hammer member and the engagement cam member make up the greater part of the mass, the momentum of which is delivered to the spindle upon impact, but the greater part of the mass is embodied in the hammer member and for that reason this member is designated as the hammer member.

A feature of the present invention is that, as opposed to prior art impact tools, the disengagement of the engagement cam member from the spindle is provided by a cam ming action and does not operate merely on impact to bring about this disengagement as has been done heretofore.

In a tool of the nature illustrated, adapted for use on nuts and screws up to about /2 inch in diameter, it is found that during free run down the air consumption is about 20 cubic feet per minute and that when the impacting commences for tightening up the nut or screw about 13 to 14 cubic feet per minute of air is used.

It will be evident from the foregoing that in any given direction of rotation, only one of the impact surfaces on the engagement cam and one of the impact surfaces on the anvil portion of the spindle are effected. Accordingly, if the tool were to be constructed for a single direction of rotation only, only one of each of said impact surfaces would be required.

Still further, it will be apparent that, for a tool that rotates in either of two directions, whenever one impact surface on each of the engagement cam member and the spindle are effective, it is the inclined surface located behind the other impact surface on the engagement cam member that serves to cam the engagement cam member back into striking position.

Thus, the cam surface for this purpose could be pro vided within the engagement cam member at a location other than the location indicated, particularly where the tool is to rotate only in one direction, or the cam surface could be provided on the spindle, and equivalent results would obtain. In any case, it will be appreciated that the functions of the cam means for camming the engagement cam member back to effective position and the impact surfaces carried by the engagement cam member and spindle, are entirely separate with regard to the basic functions of impacting and restoring the engagement cam member to effective position, and thus could be separately formed on the engagement cam member and spindle if so desired. As a matter of convenience and economy, the tool is constructed as has been illustrated.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

We claim:

1. In a rotary impact tool; a casing, a rotary spindle extending into the casing at one end, a hammer member of substantial mass rotatable in the casing and surrounding the inner end of the spindle, said hammer having a lateral bore rectangular in cross-section, a ring-like engagement cam member also rectangular in cross section freely slidably fitting said bore and having a smaller dimension laterally than the dimension of the hammer so as to be laterally slidable in said bore, said engagement cam member surrounding the inner end of the spindle and said cam and spindle having cooperating generally radial abutment surfaces engageable in one lateral-1y shifted position of said engagement cam member and being disengaged in the other laterally shifted position of said engagement cam member, the abutment surface means on said engagement cam member being parallel to the sides thereof that engage the axial surfaces of the bore in the hammer, a rotary actuator in the bore in said hammer between one end wall of the bore and the adjacent end of said cam member, said actuator having radially extending drive wing means thereon having angularly spaced substantially radial drive surfaces, and said engagement cam member having an axially extending drive tongue extending in a plane parallel with the axial surfaces of the bore and said hammer, said drive tongue extending between the said drive surfaces of the actuator and comprising radial surfaces disposed between the drive surfaces of the actuator and having a slight circumferential clearance therefrom, said actuator and hammer being relatively rotatable in one direction for caus ing lateral movement of the engagement cam in the hammer in one direction, and cooperating cam surface means on the spindle and engagement cam operable upon relative rotation between the engagement cam member and the spindle in the same direction to cause lateral movement of the engagement cam in the hammer in the opposite direction.

2. In a rotary impact tool; a casing, a spindle rotatably supported on one end of said casing having one end projecting outwardly from said casing to receive a tool and having its other end extending into the inside of said casing, a hammer of substantial mass .rotatable in said casing on the same axis as said spindle and receiving therein the said other end of the spindle, a bore extending laterally through said hammer rectangular in crosssection with axial surfaces parallel to the axis of rotation of the spindle and hammer, a ring-like engagement cam member also rectangular in cross section slidably fitting the bore in the hammer and smaller in lateral dimension than the lateral dimension of the hammer whereby the engagement cam member is shiftable laterally in the bore, the said other end of said spindle being located inside said cam member and comprising abutment surfaces thereon extending substantially radially therefrom from opposite sides of the spindle, said engagement cam member having generally radial abutment surfaces extending inwardly therefrom on opposite sides for engagement with the abutment surfaces of the spindle, said abutment surfaces being so disposed that one pair thereof are engagable when the engagement cam member is in one laterally shifted position and the other pair thereof are engagable in the other laterally shifted position of said engagement cam member, an actuator rotatable on the same axis as the spindle and disposed in the bore in the hammer between one end Wall of said bore and the adjacent end of the engagement cam member opposite the spindle end thereof, said actuator having angularly spaced radial drive surfaces thereon facing each other, said engagement cam member having an axially extending drive tongue parallel with the axial surfaces of the bore in said hammer extending into the space between the drive surfaces of the actuator and having radial surfaces thereon for engagement by the drive surfaces of the actuator when the actuator is driven in rotation, said actuator being rotatable relative to the hammer to cause lateral movement of the engagement cam member therein, and came means in the engagement cam member cooperating with said spindle for shifting the engagement cam member laterally in the hammer upon relative rotation of the spindle and engagement cam member.

3. In a rotary impact tool; a casing, a spindle extending into one end of the casing and journaled in the casing, a hammer co-axial with the spindle freely rotatable in the casing and surrounding and journaled on the inner end of the spindle, said spindle having on opposite sides of said inner end generally radial outwardly extending impact sur aces facing in opposite circumferential directions, said hammer having a transverse bore rectangular in cross-section with axial surfaces parallel to the axis of the hammer, a ring-like engagement cam having parallel fiat outer surfaces slidably fitting in said bore, said cam being laterally shifta ble in said bore between first and second extreme positions, impact surfaces extending generally radially inwardly from opposite sides of said engagement cam facing in respectively opposite circumferential directions and each forming a pair with the oppositely facing impact surfaces on said spindle, each said pair of imp-act surfaces being engageable in one only of said first and second extreme shifted positions of said cam, an actuator located in the bore of said hammer and adapted for being driven in rotation, said actuator and engagement cam being in face to face engagement in the bore in said hammer and substantially filling said bore from end to end thereof, angularly spaced substantially radial drive surfaces facing each other on said actuator, and axially extending tongue on said cam in a plane parallel with said axial surfaces extending between the drive surfaces on said actuator and having correspondingly inclined surfaces thereon for slidable engagement by the drive surfaces of the actuator whereby upon engagement of a pair of the impact surfaces and upon relative rotation between the actuator and the hammer the actuator will shift the cam in the hammer to one of its extreme positions to disengage said surfaces, an inclined surface in said cam behind each impact surface leading from the outermost edge of the pertaining impact surface to the inner periphery of the cam, and each said inclined surface cooperating with the spindle in one direction of rotation of the cam relative to the spindle to move the cam to the a a shifted position thereof in which the pertaining impact surface is effective.

References Cited in the file of this patent UNITED STATES PATENTS 2,439,756 Sheff Apr. 13, 1948 2,463,656 Thorn-as Mar. 8, 1949 2,711,662 Shah? June 28,1955 2,718,803 Jimerson Sept. '27, 1955 2,842,994 Stine -2--" July 15, 1958 

1. IN A ROTARY IMPACT TOOL; A CASING, A ROTARY SPINDLE EXTENDING INTO THE CASING AT ONE END, A HAMMER MEMBER OF SUBSTANTIAL MASS ROTATABLE IN THE CASING AND SURROUNDING THE INNER END OF THE SPINDLE, SAID HAMMER HAVING A LATERAL BORE RECTANGULAR IN CROSS-SECTION, A RING-LIKE ENGAGEMENT CAM MEMBER ALSO RECTANGULAR IN CROSS SECTION FREELY SLIDABLY FITTING SAID BORE AND HAVING A SMALLER DIMENSION LATERALLY THAN THE DIMENSION OF THE HAMMER SO AS TO BE LATERALLY SLIDABLE IN SAID BORE, SAID ENGAGEMENT CAM MEMBER SURROUNDING THE INNER END OF THE SPINDLE AND SAID CAM AND SPINDLE HAVING COOPERATING GENERALLY RADIAL ABUTMENT SURFACES ENGAGEABLE IN ONE LATERALLY SHIFTED POSITION OF SAID ENGAGEMENT CAM MEMBER AND BEING DISENGAGED IN THE OTHER LATERALLY SHIFTED POSITION OF SAID ENGAGEMENT CAM MEMBER, THE ABUTMENT SURFACE MEANS ON SAID ENGAGEMENT CAM MEMBER BEING PARALLEL TO THE SIDES THEREOF THAT ENGAGE THE AXIAL SURFACES OF THE BORE IN THE HAMMER, A ROTARY ACTUATOR IN THE BORE IN SAID HAMMER BETWEEN ONE END WALL OF THE BORE AND THE ADJACENT END OF SAID CAM MEMBER, SAID ACTUATOR HAVING RADIALLY EXTENDING DRIVE WING MEANS THEREON HAVING AN- 